Heretofore a drug component has been administered by oral administration, administration by injection, intramuscular or intravenous administration, administration to intestine or mucosa within the mouth, etc. Among them, oral administration has been most widely practiced. However, in the case of oral administration, drawbacks have occurred such that the concentration has become temporarily higher than is necessary to ensured persistence of the effect and that side effects such as stomach disorder or lack of appetite may be caused. On the other hand, although absorption is rapid in administration by injection, this must be made by an expert such as physician, etc.
Recently, dermatologic preparations by percutaneous administration have been developed to eliminate such side effects and drawbacks. However, even in such dermatologic preparations, a sufficient percutaneous absorptivity has not been yet obtained in most cases, and therefore, they are not considered satisfactory.
Further, the surface of the skin is called the skin corneum layer, which has in itself a physiological function as a barrier for protection against the penetration of foreign matter from outside of the body, and therefore, a sufficient percutaneous absorptivity can not be obtained by merely formulating a drug component in a base conventionally used in the prior art in a dermatologic preparation.
To improve this factor, various percutaneous absorption promoting agents have been proposed in recent years. For example, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, methyldecyl sulfoxide, etc., are known, but these cannot be considered to have a sufficient percutaneous absorption promoting effect, safety and use feeling.